Ribbon feed mechanism



Feb. 21, 1961 Filed July 2, 1959 B. HOWAR D RIBBON FEED MECHANISM 4Sheets-Sheet 1 CAPACIWE E a ,m

INVENTOR 552M 20 How/m0 BY ATTORNEYS Feb. 21, 1961 B, HOWARD 2,972,402

RIBBON FEED MECHANISM Filed July 2, 1959 4 Sheets-Sheet 2 INVENTOR652M42 Igor/M0 BY fiin w Mi ATTORNEY Feb. 21, 1961 v Q B. HOWARD2,972,402

RIBBON FEED MECHANISM Filed July 2, 1959 4 Sheets-Sheet 3 INVENTOR552M420 //0WA 20 Tiqfi.

BY M

Feb. 21, 1961 B. HOWARD RIBBON FEED MECHANISM 4 Sheets-Sheet 4 FiledJuly 2, 1959 INVENTOR HOW/IEO BY M v ATTORNEY:

RIBBON FEED MECHANISM Bernard Howard, Ramsey, N.J., assignor toTeleprinter Corporation, Paramus, N..l'., a corporation of New JerseyFiled July 2, 1959, Ser. No. 824,641

19 Claims. (Cl. 197-165) This invention relates to devices such astypewriters and telegraph printers using an inked ribbon.

Conventional ribbon feed mechanism employs ratchet wheels and pawlsactuated in response to the printing operation, and includes reversingmechanism to make one ratchet pawl or the other effective. In practice,this mechanism has proved to be unreliable compared to the mainmechanism of the printing machine, and has caused a disproportionatelygreat amount of breakdown and maintenance.

One primary object of the present invention is to gener ally improveribbon feed mechanisms. A more particular object is to provide such amechanism which is inexpensive, reliable, and self-contained in that itemploys its own motor. Despite the use of a motor, the remainingmechanism is so inexpensive and simple that the overall cost is reducedand reliability is increased. A further object is to provide mechanismwhich will use a standard typewriter spool.

To accomplish the foregoing general objects, and other more specificobjects which will hereinafter appear, my invention resides in theribbon feed mechanism and the elements thereof and their relation one toanother, as are hereinafter more particularly described in the followingspecification. The specification is accompanied by drawings, in which:

Fig. 1 is a partially sectioned elevation of mechanism embodyingfeatures of the invention;

Fig. 1A shows a fragment of Fig. -1 drawn to enlarged scale;

Fig. 2 is a section taken approximately in the plane of line 2-2 of Fig.1;

Fig. 3 is a schematic plan view showing how the invention may be appliedto a typewriter;

Fig. 4 is a wiring diagram explanatory of the con nections to thereversible motor;

Fig. 5 is a section similar to a portion of Fig. 1 but showing amodification which reduces the axial separation of the spools;

Fig. 6 is a fragmentary elevation which supplements Fig. 5 by showingthe stop pawl;

Fig. 7 is a fragmentary section taken in the plane of line 77 of Fig. 6;

Fig. 8 is a front elevation of a modified form of the invention usingspools which may be of equal diameter and both of which may be standard;

Fig. 9 is a section taken approximately in the plane of the-line 9-9 ofFig. 8; and

Fig. 10 shows the friction clutch portion of Fig. 9 drawn to enlargedscale.

Referring to the drawing, and more particularly to Figs. 1 and 2, theribbon feed mechanism comprises a first ribbon spool 12 and a reversibleelectric motor 14. This motor is a very slow-speed motor or so-calledclocktype motor the final shaft of which turns only a few revolutionsper minute. The motor drives 'the spool through appropriate means whichin this case is simply a shaft 16 fitted with a conventional spool lock18 to hold Patented Feb. 21, 1961 ICE the spool 12 on the shaft, andalso fitted with a driving pin 20 which engages the spool to drive thesame. The spool 12 is preferably a standard typewriter spool.

The mechanism further comprises a second ribbon spool 22 which is driventhrough frictional slip drive means generally designated F, the saidmeans being disposed between the first spool 12 and the second spool 22.This drive means includes a wheel 24 and a friction disc 26 between thewheel 24 and the spool 22. The arrangement is such that the frictiondrive means F attempts to drive the spool 22 at a linear ribbon speedwhich is higher than that of the first spool 12, when the first spool isacting as a supply spool and the second spool 22 is acting as a take-upspool.

The wheel 24 is associated with a means 30 to prevent rotation of thewheel in opposite direction, and because of this the friction drivemeans F becomes a friction brake means holding back the second spool 22when it acts as a supply spool while the first spool 12 acts as atake-up spool, i.e., when the direction of rotation of motor 14 has beenreversed.

In the present case, the wheel 24 is. a ratchet wheel, and the means 30is a pawl engaging the ratchet wheel, as is best shown in Fig. 2.

In the form of the invention here shown, the second spool 22 has adiameter larger than that of the first spool 12'. Indeed, the minimumdiameter of spool 22 with no ribbon thereon is preferably equal to andmay be larger than the maximum diameter of spool 12 with a full ribbonwound thereon. 'Moreover, in this form of the invention the spools arecoaxial, as shown. The .friction drive mechanism F tends to rotate bothspools at the same rotative speed. It is the difference in diameter ofthe spools that provides the desired higher linear ribbon speed (meaningtheattempted speed) referred to above.

In Fig. 1,'the ribbon leaves the top of spool 12 as shown at 32', andpasses over ribbon guides 34 and 36 (Fig. 2), and thence back to thebottom of spool 22, as shown at 38 (Fig. 1). In the particlular printerhere shown the type is formed on an eight-sided type cylinder 40 (Fig.2), and the printing operation is caused by a hammer 42 which strikesthe ink ribbon at 44 against the paper .46 which in the present case isa narrow tape moving inhorizontal direction while the ribbon is movingin vertical direction. Oneadvantage of the present ribbon feed mechanismwith its independent motor drive is its great flexibility, it beingadapted to installation in all kinds of printers with little or nomodification of the feed mechanism, because the ribbon guides whichbring the ribbon'to the paper, and the electrical connections, are theonly external connections other than physical mounting of the motormechanism somewhere in or on the printer.

Fig. 3 schematically represents an ordinary typewriter viewed in plan.The paper roll or carriage is suggested at 50, while the keyboard islocated at 52. The ribbon 54 is wound on smaller and larger coaxialspools 56 and 58; A ribbon guide is provided at 60, instead of a spoolas in an ordinary typewriter. At the printing point 62 the ribbon passesthrough a conventional ribbon support which raises and lowers the ribboneach time a character is printed. It will be evident that the mechanism56, 58 may correspond to that described above, the main dilference beingthat the spool axis is vertical instead of horizontal.

Reverting now to Fig. l, a reversing switch for the motor 14 is shown at64. It is preferably of the over-thecenter or toggle type, so that itremains closed in one direction or the other. It may be actuated by arocker arm or lever 66 pivoted at 68 and providing ribbon slots at itsends. In the present case, one end carries a pair of closely adjacentcollateral pins or posts 70 which form one ribbon slot, and the otherend carries a similar pair of pins 72 which form theother ribbon slot.The arrangement will be understood from inspection of Fig. 2 which showsa lever 66 which oscillates or rocks on a centerpivot 68. Pins 70 aremounted at one end of lever 66, and pins 72 at its other end. The part32 of the ribbon passes between the pins 72, and the part 33 passesbetween the pins 70.

As is usual, the pins or ribbon slots are dimensioned to freely pass theribbon, but not to pass an eyelet or like means conventionally securednear each end of the ribbon in order to cause reversal of the ribbonfeed. In Fig. 2 the part 32 of the ribbon is moving to the left, andwhen the end of the ribbon has been nearly reached an eyelet on theribbon engages the pins 72 and carries the tiltable rock arm with it.This causes a bifurcation 74 to move downward and thus to trip thereversing switch from one position to its opposite position, where itremains until the opposite end of the ribbon with its eyelet reaches theribbon slot 70, which then is in its right-hand position and is moved bythe eyelet to the lefthand position shown.

The motor here used is a series RSM synchronous reversible motor made byHurst Tool and Mfg. Co., Inc., of Princeton, Ind. It includes reductiongearing such that its output shaft, marked 89 in Fig. 1, turns at onlysix rpm. The motor is a single-phase motor, but a capacitor is used todisplace the phase in two parts of the field. The arrangement isindicated in Fig. 4, in' which the field is represented by coils 82 and84. The capacitor is shown at 86, and the reversing switch 64 is asingle pole, double-throw switch. When connected to the upper contact,the coil 84 leads and the coil 82 lags in phase; and conversely, whenswitch 64 is closed to its lower contact the coil 82 leads and the coil84 lags in phase. Thus, the field rotates in one direction or the otherand causes corresponding rotation of the rotor.

Reverting to Fig. 1, and considering the mechanism in greater detail,shaft 16 has a socket 911 which is secured to motor shaft 80 by means ofa set screw 92. Shaft 16 carries a driving chuck 94 with its pin 20, andthese are secured to the shaft by means of a set screw 96. Ratchet wheel24 (Figs. 1 and 1A) is smooth on both faces and is freely rotatable onthe sleeve or hub portion of chuck 94. The friction disc 26 is anannulus or ring partly received in one face of spool 22, and bearingdirectly against one side of ratchet wheel 24. The desired frictionalengagement preferably is maintainedby means of a spring disc or washer98 disposed between chuck 94 and ratchet wheel 24. It will be evidentthat this urges the ratchet wheel axially into engagement with thefriction disc 26.

The standard ribbon spool 12 is positively driven in one direction orthe other by the motor. When starting a new ribbon, the large spool 22acts as a take-up spool. Its attempted one-to-one drive is too fastbecause of its larger diameter, and instead it slips and takes up theribbon only as fast as it is fed from the supply spool 12. When all ofthe ribbon has been transferred from spool 12 to spool 22, the directionof feed is reversed, whereupon the spool 12 winds the ribbon under motordrive. The spool 22 then would unwind the ribbon much too fast if itwere driven as before by the spool 12, but instead the friction drive Fis automatically converted from a friction drive to a friction brake bythe action of the stop pawl 30, which holds the ratchet. Wheel 24stationary. The friction disc 26 then becomes a brake disc which tendsto hold the spool 22 back, so that it releases ribbon only to the extentthat the ribbon is pulled from it by the motor drive of spool 12.

A slightly modified construction is shown in Figs. 5, 6, and 7 of thedrawings. This is substantially the same as the mechanism shown in Fig.1, except that axial displacement between the two spools has beenreduced by housing the friction drive parts F within the large spool.

In Fig. 5 the spool 112, motor 114, shaft 116, spool lock 118, and drivepin 12! all correspond to the parts shown in Fig. 1, except that shaft116 is somewhat shorter. The spool 122 is hollowed or recessed at 123 toreceive the ratchet wheel 124 and friction disc 126. The spring washeris shown at 127 and exerts axial pressure between the chuck 128 and theratchet wheel 124.

The upper end of the stop pawl 130 has been broken away in Fig. 5, butis better shown in Fig. 6. It has an offset or inwardly directed tooth132 which engages the ratchet wheel 124. These parts are also shown inFig. 7.

In theory a ratchet wheel could be used alone as a friction drive means.The friction disc helps provide the desired friction but is notessential. The spring washer helps maintain a desired uniform friction,and compensates for wear of the parts, particularly the friction disc.

As so far described, the spools tend to turn at the same speed, butdiffer in diameter. In Figs. 8, 9, and 10 I show another form of theinvention in which the spools are of the same diameter but tend to turnat different speeds. Referring to Fig. 9, the first ribbon spool 142 isdriven by a reversible electric motor 144, which may be the same as thatpreviously described. The spool 142 is carried on a shaft 146 havingspool lock 148 and a driving pin 150. These parts are secured to motorshaft 152 by means of a socket 154 with a set screw 156.

The second ribbon spool is shown at 158 and may have the same diameteras spool 142. They preferably are both standard typewriter spools. Spool158 is mounted on a shaft 160 having a spool lock 162. Shaft 161 is nota drive shaft, and it may be stationary with its other end riveted at164.

As before, there is a frictional slip drive means between spool 142 andspool 158, and this attemptsto drive spool 158 at a higher speed. Forthis purpose the drive means includes step-up gearing. In the presentcase, shaft 146 carries a gear 166 meshing with an idler 168 whichmeshes with a gear 170. The latter is smaller in diameter than gear 166,and is driven at higher speed. The difierence in diameter is made enoughto compensate for the difference between the diameter of an empty ribbonspool and a filled ribbon spool.

As before, the friction drive means includes a ratchet wheel 172. A disc174 is disposed between the ratchet wheel and the spool 158, and disc174 has a drive pin 175. There is also a spring washer 176 (Fig. 10)between gear and ratchet wheel 172, thus urging all of the parts intofrictional engagement. The stop pawl which prevents reverse rotation ofthe ratchet wheel.172 is shown at 178 (Figs. 8 and 9).

In Fig. 8 the spool 142 is acting as a supply spool, and the spool 158is acting as a take-up spool. The motor is driving spool 142 incounterclockwise direction. The ribbon passes round a ribbon guide 130and then through a ribbon slot 182 and thence around a ribbon guide 184to a printing point which may be at the region 186. The ribbon continuesaround a ribbon guide 188 and through a ribbon slot 190 and thencearound ribbon guide 192 to the take-up spool 158. Although the latter isempty and of small diametenthere is no slack because it is turned at ahigher rotative speed by reason of the step-up gear ratio mentionedabove.

The smooth round pins forming the ribbon slots are carried at the endsof a tiltable rock arm 194 pivoted at 196. The reversing switch 198 is asingle pole doublethrow switch which is moved over the center to oneside or the other by a bifurcation200 in arm 202, carrying the tiltablelever 194-.

It will be evident that when the end of the ribbon is approached, aneyelet on the ribbon will reach the ribbon slot 182 and tilt the upperend of arm 194 from its right-hand to its left-hand position, therebymoving the lower end from left-hand to right-hand position, andreversing the switch and consequently the motor. Spool 142 becomes atake-up spool which pulls ribbon grad ually from spool 158 which thenacts as a supply spool. At this time, the stop pawl 1-78 automaticallytakes efiect and the friction drive is converted to a friction brakewhich serves to hold back the supply spool 158.

It will be understood that while the'spools have been shown coaxial inFig. l, and displaced from one another in Fig. 8, this is not essential;and spools which are of different diameter and tend to turn at the samespeed may be mounted on displaced axes; and, conversely, spools whichare equal in. diameter but which are turned at different speeds may bemounted in coaxial relation.

It is believed that the construction and operation of my improved ribbonfeed mechanism, as well as the advantages thereof, will be apparent fromthe foregoing detailed description. The mechanism is self-contained andis adapted to be used on widely different kinds of printing mechanisms,with little or no modification. Despite the cost of the motor, thenecessary mechanism is so inexpensive, and the manufacturing tolerancesare so great, that the total cost is less than that of conventionalribbon feeds. The present ribbon feed is reliable, and eliminates acause of frequent service complaints when using conventional ribbonfeeds. The mechanism may be used with standard and non-standard ribbonsand spools.

It will be understood that while I have shown and described my inventionin several preferred forms, changes may be made in the structures shown,without departing from the scope of the invention as sought to bedefined in the following claims.

In the claims the term ribbon is not intended to include other forms oftape.

I claim:

1. A ribbon feed mechanism comprising a first ribbon spool, a reversiblemotor, means causing said motor to drive said spool at slow speed, asecond ribbon spool, rotatable friction slip drive means between thefirst spool and the second spool arranged to attempt to drive the secondspool in one direction at a linear ribbon speed higher than that of thefirst spool when the first spool is acting as a supply spool and thesecond spool is acting as a take-up spool, and means cooperating withsaid friction drive means to prevent rotation in the opposite direction,whereby said friction drive means becomes a friction brake means holdingback the second spool when it acts as a supply spool while the firstspool acts as a take-up spool.

2. A ribbon feed mechanism comprising a first ribbon spool, a reversibleelectric motor, means causing said motor to drive said spool positivelyat slow speed, a second ribbon spool, friction slip drive meansincluding a ratchet wheel between the first spool and the second spoolarranged to attempt to drive the second spool in one direction at alinear ribbon speed higher than that of the first spool when the firstspool is acting as a supply spool and the second spool is acting as atake-up spool, and a stop pawl engaging said ratchet wheel to preventrotation in the opposite direction, whereby the friction drive meansbecomes a friction brake means holding back the second spool when itacts as a supply spool while the first spool acts as a take-up spool.

3. A ribbon feed mechanism as defined in claim 1 in which the secondspool has a diameter larger than that of the first spool, in order toprovide the desired higher linear ribbon speed.

4. A ribbon feed mechanism as defined in claim 2 in which the secondspool has a diameter larger than that of the first spool, in order toprovide the desired higher linear ribbon speed.

5. A ribbon feed mechanism as defined in claim 1 in whichv the secondspool has a diameter larger than that of the first spool, the minimumdiameter of the second spool with no ribbon thereon being at least aslarge as the maximum diameter of the first spool with a full ribbonthereon.

6. A ribbon feed mechanism as defined in claim 2 in which the secondspool has a diameter larger than that of the first spool, the minimumdiameterof the second spool with no ribbon thereon being at least aslarge as the maximum diameter of the first spool with a full ribbonthereon.

7. A ribbon feed mechanism as defined in claim 1 in which the first andsecond spools and the friction drive means are disposed coaxially, andin which the first spool is a standard typewriter ribbon spool.

8. A ribbon feed mechanism as defined in claim 2 in which the first andsecond spools and the friction drive means are disposed coaxially, andin which the first spool is a standard typewriter ribbon spool.

9. A ribbon feed mechanism as defined in claim 1 in which the secondspool has a diameter larger than that of the first spool, the minimumdiameter of the second spool with no ribbon thereon being at least aslarge as the maximum diameter of the first spool with a full ribbonthereon, and in which the first and second spools and the friction drivemeans are disposed coaxially, and in which the first spool is a standardtypewriter ribbon spool.

10. A ribbon feed mechanism as defined in claim 2 in which the secondspool has a diameter larger than that of the first spool, the minimumdiameter of the second spool with no ribbon thereon being at least aslarge as the maximum diameter of the first spool with a full ribbonthereon, and in which the first and second spools and the friction drivemeans are disposed coaxially, and in which the first spool is a standardtypewriter ribbon spool.

11. A ribbon feed mechanism as defined in claim 1 in which the drivemeans between the first and second spools includes step-up gearing forattempting to drive the second spool at a higher rotative speed than thefirst spool.

12. A ribbon feed mechanism as defined in claim 2 in which the drivemeans between the first and second spools includes step-up gearing forattempting to drive the second spool at a higher rotative speed than thefirst spool.

13. A ribbon feed mechanism as defined in claim 1 in which the first andsecond spools have the same di ameter when empty, and in which the drivemeans between the first and second spools includes step-up gearing forattempting to drive the second spool at a higher rotative speed than thefirst spool.

14. A ribbon feed mechanism as defined in claim 2 in which the first andsecond spools have the same diameter when empty, and in which the drivemeans between the first and second spools includes step-up gearing forattempting to drive the second spool at a higher rotative speed than thefirst spool.

15. A ribbon feed mechanism as defined in claim 1 in which the first andsecond spools are both standard typewriter ribbon spools having the samediameter, and in which the drive means between the first and secondspools includes step-up gearing for attempting to drive the second spoolat a higher rotative speed than the first spool.

16. A ribbon feed mechanism as defined in claim 2 in which the first andsecond spools are both standard typewriter ribbon spools having the samediameter, and in which the drive means between the first and secondspools includes step-up gearing for attempting to drive the second spoolat a higher rotative speed than the first spool.

17. A ribbon feed mechanism as defined in claim 1 inwhich the motor isan electric motor, and further comprising a reversing switch for saidmotor, and a switch actuator including a tiltable rock arm which ispivoted in the middle and which has a ribbon slot in each end, one ofsaid ribbon slots receiving the ribbon adjacent one spool and the otherribbon slot receiving the ribbon 7 adjacent the other spool, said slotsbeing dimensioned to freely pass the ribbon but not ,the conventionaleyelet or like means conventionally secured near each end of the ribbonto cause reversal of the ribbon feed.

18. A ribbon feed mechanism as defined in claim 2 and further comprisinga reversing switch for said motor, and a switch actuator including atiltable rock arm which is pivoted in the middle and which has a ribbonslot in each end, one of said ribbon slots receiving the ribbon adjacentone spool and the other ribbon slot receiving the ribbon adjacent theother spool, said slots being dimensioned to freely pass the ribbon butnot the eyelet or'like means conventionally secured near each end of theribbon to cause reversal of the ribbon feed.

19. A ribbon or tape feed mechanism comprising a first spool, a secondspool coaxial with the firstspool, and means whereby the first spoolattempts to drive the second spool at a linear speed higher than thefirst spool, with the first spool acting as a supply spool and thesecond spool acting as a take-up spool, said means including africtional slip drive means between the first spool and the secondspool.

References Cited in the file of this patent UNITED STATES PATENTS1,628,164 Lippert May 10, 1927 2,609,077 Schroder Sept. 2, 19522,889,909 Rehurek June 9, 1959

